Here’s the recipe for caramel color: Create a chemical reaction of sugars with ammonia — yes, ammonia — and sulfites under high pressure and temperatures to form 2-methylimidazole and 4-methylimidazole.

These ingredients don’t just sound scary: They cause cancer, according to several government studies on lab animals. In California, 4 MI is listed as a known human carcinogen.

The Center for Science in the Public Interest is urging the FDA to ban caramel colors created with ammonia and sulfites, arguing that the risk of cancer, while relatively small, is not warranted by the ingredients’ purely cosmetic function. If the agency won’t ban 2 MI and 4 MI, CSPI wants it at least to demand that cola makers call the ingredients “ammonia sulfite process caramel” instead of the natural sounding “caramel color.”